1. Field of the Invention
The present invention relates to a liquid-droplet ejecting apparatus, and particularly to a liquid-droplet ejecting apparatus including a gas-permeable film.
2. Description of Related Art
Some of the liquid-droplet ejecting apparatuses including a liquid ejecting head for ejecting droplets of a liquid, such as inkjet printer, further include a liquid supply passage through which the liquid is supplied to the liquid ejecting head, as disclosed in JP-A-2005-288770 (see especially FIG. 2). The apparatus disclosed in this publication includes a carriage, a recording head mounted on the carriage, a sub tank, an ink cartridge, and a suction pump. The ink cartridge stores an ink to be supplied to the recording head via the sub tank and an ink supply passage.
The sub tank in this apparatus has a gas-permeable film. The gas-permeable film does not allow the ink to pass therethrough, but selectively allows gas or air to pass therethrough. By having the suction pump suck a gas or an air from an inside of the sub tank through the gas-permeable film, the sub tank is depressurized, or an internal pressure of the sub tank is decreased, thereby introducing the ink from the ink cartridge into the inside of the sub tank. Further, after the apparatus is turned off, the gas or air suction from the inside of the sub tank is implemented in order to have the gas or air bubbles flown out of the ink. Thus, the gas or air contained in the ink stored in the sub tank is separated from the ink, or “gas-liquid separation” is implemented on the ink in the sub tank, so as to inhibit inflow of the gas or air into the liquid ejecting head.
In this apparatus, however, after once implemented at the time of introduction of the ink into the sub tank, the gas or air suction from the sub tank is not performed until the apparatus is turned off. Hence, when the recording head is operated to record an image after the introduction of the ink into the sub tank, gas or air bubbles continue to occur in the ink and accumulate in the sub tank, adversely affecting the depressurized state of the sub tank and accordingly inhibiting separation of the gas or air bubbles from the ink. The thus invited insufficiency in the gas-liquid separation in the sub tank may result in undesirable inflow of the gas or air together with the ink into the liquid ejecting head.